/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.feilong.lib.lang3.time;

import java.util.Date;
import java.util.TimeZone;

/**
 * Custom timezone that contains offset from GMT.
 *
 * @since 3.7
 */
class GmtTimeZone extends TimeZone{

    private static final int MILLISECONDS_PER_MINUTE = 60 * 1000;

    private static final int MINUTES_PER_HOUR        = 60;

    private static final int HOURS_PER_DAY           = 24;

    // Serializable!
    static final long        serialVersionUID        = 1L;

    private final int        offset;

    private final String     zoneId;

    GmtTimeZone(final boolean negate, final int hours, final int minutes){
        if (hours >= HOURS_PER_DAY){
            throw new IllegalArgumentException(hours + " hours out of range");
        }
        if (minutes >= MINUTES_PER_HOUR){
            throw new IllegalArgumentException(minutes + " minutes out of range");
        }
        final int milliseconds = (minutes + (hours * MINUTES_PER_HOUR)) * MILLISECONDS_PER_MINUTE;
        offset = negate ? -milliseconds : milliseconds;
        zoneId = twoDigits(twoDigits(new StringBuilder(9).append("GMT").append(negate ? '-' : '+'), hours).append(':'), minutes).toString();

    }

    private static StringBuilder twoDigits(final StringBuilder sb,final int n){
        return sb.append((char) ('0' + (n / 10))).append((char) ('0' + (n % 10)));
    }

    @Override
    public int getOffset(final int era,final int year,final int month,final int day,final int dayOfWeek,final int milliseconds){
        return offset;
    }

    @Override
    public void setRawOffset(final int offsetMillis){
        throw new UnsupportedOperationException();
    }

    @Override
    public int getRawOffset(){
        return offset;
    }

    @Override
    public String getID(){
        return zoneId;
    }

    @Override
    public boolean useDaylightTime(){
        return false;
    }

    @Override
    public boolean inDaylightTime(final Date date){
        return false;
    }

    @Override
    public String toString(){
        return "[GmtTimeZone id=\"" + zoneId + "\",offset=" + offset + ']';
    }

    @Override
    public int hashCode(){
        return offset;
    }

    @Override
    public boolean equals(final Object other){
        if (!(other instanceof GmtTimeZone)){
            return false;
        }
        return zoneId == ((GmtTimeZone) other).zoneId;
    }
}
